Manufacture of portland cement.



T. A. EDISON.

MANUFACTURE OF PORTLAND CEMENT.-

. APPLIOATION FILED MAY 8, 190a Patented Apr. 22, 1913.

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Y Specification of Letters Patent. Patented Apr. 22, 1913.

Application filed May 8, 1 906. Serial No. 315,717.

To (ill whom it may concern: Y Be it known that 'I, THOMAS A; EDISON,

a citizen of the. United States, residing at Llewellyn Park, Orange, county of Essex,

"and State'of New Jersey, have invented certain new and useful- Improvements inthe Manufacture of Portland Cement, of which the following is a description.

My invention relates to an improved process for manufacturing Portland cement-, -and my object is: the production of a process for the pur ose which can be economically and 'vdiy practised in l calities where the conditions as to raw material are unfavorable forworking by present methods.

- In general, the invention consists in manu- 1 facturingartificially a cement'making material similar in its chemical and physical properties to the best natural cement rock, as

found for example, 'in eastern Pennsylvania.

and north-western New Jersey; said mate rial being "subsequently admixed with a proper proportion of limestone, and,- after grinding, being burned in a cement kiln,-as

in; modern cement-making processes.

'- Broadly speaking, the invention consists in forming a cement making material or 'production of Portland cement), by slag; glngor fusing the correct proportions of 'si-' natural cement rocli (adapted to be inti mately mixed with the proper proportion of limestone to result, after calcinatlon, in the licious material, such as quartz, with a sufiiciently low percentage of limcstone in; the

presence of alumina (for instanceclay)and 1ron,'so as to therebyresult ina very fluid slag-such fusiontaking place in a suitable water-jacketed furnace for the purpose, the

' fluidslag being tapped oil at the bottom. of the furnace andbemg finely subdivided ordisintegrated, for instance, by a powerful jet. of compressed air or steam, or by centrifugal force. I find that it. is possible to,

artificially make cement rock in this way at a sufiiciently low temperatureto enable the process to be carried on in an economical 'wayand on an entirely practical scale, so.

that when the material is intimately added to finely powdered limestone and burned-in a rotary kiln, or otherwise, Portland cement,

Hof'excellent quality can be securedf While it would be possible to intimately mix proper proportionsof raw materials (silica, alumlna, iron and lime) as to result in Port? land cement after burning in a rotary kiln,

the expense of fine grinding the silicious inobjectionable impurities.

numerals of reference.

t of the. sla ing operation which is therefore preferre I am of course aware that heretofore Portland cement has been made from slag obtained in the operation of blast furnaces,

I gredients, sujhas quartz, would more than 1 ofiset the es but with these latter processes, the slag is seldom suitable'for'the purpose and generally contains sulfur 0r otherobjectionable impurities, and even when the slag is capable of use for cement purposes, the resultin cement is very irregular in quality. With my improved process, the slag, instead of being anxirregular and uncertain by-produet, is the direct product of the operation, and

hence the in redients can be always selected so as to resu t in a perfect material free from consideration in the processjis the use of a sufiiciently low percentage of lime as to enable the slagging operatlon to. be carried on at an economical temperature,'while at the same'time the resulting slag can be made extremely liquid and non-vis'cid, and hence can be readily blown or disintegrated into a fine 1 powder. If it were attempted to add a sufficient amount of limein the first instance to make Portland cement, the tempei ature requiredfor its fusion would be from 2500 degrees to 3000 degrees Fahn, a temperature far too high to enable the operations to be carried on with any degree of commercial economy.

{.In order that the invention may be better understood, attention is directed to the ac- The important companying drawing, forming 'part of this In carrying the invention into effect, I introduce Into the; furnace 1,- successive charges of cement making' material, to whi h.

is added 'coal or coke in the proper amount to effectthe fusion. Quartz may -be employed as the source of silica, and clay as thesource of alumina.- i

A smallJpercentage of oxid of iron is also employed, as well as limestoneyin suflicient amount to permit fusion at an economically by the same 'low temperature.

Suitable proportions are the follow1ng1-- I SiO i 32% CaO 50% Fe and Al 13% Mg, alkali, etc 5%" 'lhese percentages of ingredients may, how-' ever, be varied, depending on the price of coal, and upon the amount of potashin the natural materials, the presence f pot-ash serving to increase the fusibility o the slag.

The materials"containing these substances 1 are broken .up into lumps and are fed to the I necessary for fusion of the specific composition mentioned above is approximately 1800 degrees to 2000 degrees Fahr. As the material fuses the very liquid slag is tapped oil t-hrough' a pipe 3. The flow, of the slag from the pipe 3 may be controlled by a plug of clay, in the usual way. The liquid' as it falls, may be subjected to the eifect of a powerful blast of compressed air or steam from a pipe 4:, by which the liquid will be finely subdivided and blown into a large 'settlmg chamber 5, so as to deposit therein asa fine powder;

Insteadof subdividing the liquid slag by a jet, as explained, it may be allowed to fall .on a rapidly rotating wheel 6, by which it will be thrown off bycentrifugalforce into the settling chamber 5, and finely subdi videdin this .way. The fine powder deposited in the settling chamber is new intimately admixedwiththe proper proportion of powdered limestone to bring the lime .contents upto the desired formula for Portland cement, and the hhalk-like' compound thus secured is then clinkeredi in a suitable rotary cement kiln, or 1 otherwise. If -de-. sired, the material collected in the settling chamber, not sufliciently fine and uniform, may be first ground and properly sized by screening or blowing, after which it may be then mixed with the powdered limestone.

Having now described my invention, what I claim as new and desire to secure by Letters Patent is as follows 1'. The process of manufacturing Portland cement, which consists infusing silicious and aluminous materials" with-lime- 60 fusion ata temperature less than. 2500de grees Fahr. and the production of exstone in such proportions as to result in tremely liquid non-yiscid slagof fixed- 'pro portions, in finely subdividing'the :slag' thus obtained, in adding suficient limestone to complete the 'finalproportion of lime desired for the cement, and in finally calcining the mixture, substantially as set forth.v

2. The process of manufacturing Portland cement, which consists in fusing silicious and 'aluminous materials with limestone in such proportions as to'resultin fusion at a temperature of approximately 2000 degrees l ahr. and the production of an extremely liquid uon-viscid slagof fixed proportions, .iini finely subdividing the slag thus obtained, in adding suflicient limestone to complete the final proportion of lime desired for the cement, and in finally calcining the mixture, substantially as setforth.- i

3. The process of manufacturing Portland cement, which consists in fusing silicious and aluminous materials with limestone in such proportions as to result in an extremely liquid and non-viscid slag containing approximately, 50% of lime, in finely subdividing the slag thus bbtained, in adding sufficient limestone to complete the final proin finally calcining the mixture, substan- 'tially as set forth.

cement, which consists in fusing silicious and aluminous materials with limestone .in such proportions as to result in fusion ata temperature less than 2500 *degrees Fahr. and the production ofan extremely liquid non-viscid slag containing approximately 50% of lime, in finely subdividing the slag thus obtained, ,in adding suflicient limestone to complete the final proportion of lime dethe mixture, sub'stantially as set forth.

cement, which consists in fusing silicious and aluminous materials with limestone in such proportions as to result in fusion at a temperature less "than 2500 degrees Fahr.

'non-viscid slag, containing approximately 50%oflime, in subjecting the fluid slag to a powerful blast whereby it will be chilled and finely subdivided, in adding suflicient limestoneto complete the final proportion of lime desired for the cement, and in finally cfaalcilpingthe mixture, substantially as set ort land cement, which consists in fusing silicious, aluminous, ferrous, and alkaline materials with limestone in such proportions as to result in fusion at a temperature less than 2500 degrees Fahr. and the production of an extremely liquid non-viscid slag of .fixed'proportions, in finely sub-dividing the slag thus obtained, in adding suflieient limestone to complete thefinalproportion of lime desired for cement, and in finally cal- ,g h mixture, substantially as set forth; iv .4. The process of manufacturing Portland 5. The process of manufacturing Portland and the production of an extremelyliquid 6. The process of manufacturing Portportion of lime desired for; the cement, and

. sired for the cement, and in finally calcining III i 7. The process of manufacturinPortland cement, which consists in fusing silicious,

aluminous, ferrous, and suitable alkaline materials with limestone in such proportions as to result in the reduction of an extremely liquid non-viscid slag comprising materials in the following proportions: silica, approximately 32%; lime, approximately 50%; iron and aluminum, approxi- 10 mately 13% and magnesium, alkali, etc. a

proximately 5%, in finely sub-dividing t e till;

slag thus obtained,in addin suflicient limestoneto complete the fina proportion of lime desired for the cement, and in finally calcining the mixture, substantially as set forth.

This s ecification signed andv witnessed this 7th ay of May 1906.

v THOMAS A. EDISON.

Witnesses:

FRANK L. DYER, ANNA R. KLEHM. 

